The present invention relates to a travel limiting element in a brake booster device for a motor vehicle brake system, comprising a pair of longitudinal legs which are connected together via at least one transverse leg, wherein the travel limiting element can be brought into contact with a stop of the brake booster device.
Travel limiting elements of this kind, also called “crossbars” in technical jargon, are already known from the prior art. Thus the document EP 0 327 997 A2 presents a pneumatic brake booster of tandem design in which the transmission piston arrangement is constructed with a crossbar. This crossbar is in contact with the booster housing when the brake booster is in a starting position. It can be displaced together with the control piston arrangement in an opening inside the control valve housing. It thereby on the one hand limits the relative movement between the control piston arrangement and the control valve housing and on the other guarantees a defined starting position by bearing against an associated stop on the housing wall.
The mode of operation of brake boosters of this kind and in particular the function of a travel limiting element of this kind, called a crossbar, are well-known in the prior art.
Also to be referred to as prior art is the document DE 103 42 452 A1, which presents a comparable crossbar.
It has become apparent that crossbars of this kind have to bear relatively large loads, so that they must be made of an appropriately stable material, in particular of a heavy tough metal material. Crossbars of this kind are usually made in a stamping production process. Since, as described above, the crossbars come into and out of contact with different stops on the housing of the brake booster as well as on the control valve housing during operation, when the crossbars are of a purely metallic construction undesirable noises occur during operation, i.e. upon actuating the brake. In order to prevent noises of this kind, attempts have in the past been made to provide the crossbars or the stops with an appropriately noise-damping coating, which has made production more complicated and expensive.
As opposed to this, a feature of the present invention is to provide a travel limiting element of the type initially described which, while being of a simple and cost-effective design, nevertheless affords sufficient stability for absorbing the occurring forces.